Tablesaws, shapers and router tables are frequently provided with a fence for guiding a workpiece relative to a rotary cutting tool. For example, in a tablesaw, the rotary blade will project upward through a slot in the surface of the table, a rip fence will be oriented parallel to the blade and shiftable toward and away therefrom. The rip fence typically spans between a front and a rear guide rail which runs along the front and rear marginal edges of the table, generally perpendicular to the plane of the saw blade when in the vertical orientation. In order to accurately locate the rip fence relative to the blade, a scale is typically provided on the guide rail and a corresponding pointer is provided on the fence. In order to increase positioning accuracy when moving the fence, the pointer on the fence will often be provided with a cylindrical lens to magnify the scale indicia.
If it is desired to move the fence 1/8 of an inch toward the blade, the fence is unlocked by releasing a fence locking handle. The user will then tap the fence or the fence front block until the scale pointer indicates an 1/8 of an inch movement and the fence is then relocked in place. It is difficult, however, to make accurate adjustments much less than 1/16 of an inch due to the natural limitations of the scale and pointer measurement system and the fact that the fence will sometimes move slightly when the locking handle is secured.
A typical tablesaw employing a conventional fence is shown in U.S. Pat. No. 5,116,249. A tablesaw which the preferred embodiment of the present invention was specifically adapted to cooperate with is illustrated in Ryobi Owner's Operating Manual 10" Tablesaw/BT3000, circa 1991, which is incorporated by reference herein. Specifically, on pages 32 and 36 of the Owner's manual, the general construction of a saw table and front and rear rails is shown as well as the construction of a typical rip fence assembly.